Numerical predictions of flow and thermal fields in an enclosure with two periodically moving walls

Numerical predictions of transient flow and thermal fields in a rectangular enclosure with two periodically moving vertical walls are presented. The combined influence of the movement of the walls and the buoyancy as well on the flow pattern and heat transfer performance is evaluated. The compressible‐flow model is adopted, and governing equations are expressed in integral form and discretized on the moving grids, which deform in resonance with the walls to accommodate the variation in the volume of the enclosure. A two‐stage pressure‐correction scheme is applied for simultaneously determining the distributions of absolute pressure, density, temperature, and velocity of the compressible flow field in the enclosure during the periodically stable periods. Effects of the frequency, stroke, and the phase angle of the wall oscillations on the flow are of major concerns in this study. The frequency is ranged between 5 and 25 Hz and the dimensionless strokes (l/H) of the wall are varied from 0.4 to 1.0. Results for Nusselt numbers on the walls as well as the dimensionless input work required to excite the wall oscillation are provided. Copyright © 2006 John Wiley & Sons, Ltd.